The present invention relates to a device for protecting lifting inserts having a tubular body during their embedding in a prefabricated concrete component.
Lifting inserts are known which are substantially constituted by a tubular body that is embedded in the concrete body of a prefabricated component during its production, so that an open axial end of the insert is flush with one face of the component or in any case proximate to one face of the component, so that an element to be used to lift the component can be inserted in such axial end.
In order to allow insertion of such element in the tubular body, at least one inner portion of the tubular body, starting from said axial end thereof, must be free from concrete. For this reason, during the production of the prefabricated component it is necessary to take particular care so that the concrete does not invade the internal portion of the tubular body designed to receive said element.
A lifting insert of the above cited type is disclosed in U.S. Pat. No. 6,092,849 by the same Applicants. Such lifting insert is substantially constituted by a tubular body in which an axial portion of its extension is flattened, starting from the axial end that must be accessible by the element for lifting the component, while the remaining part has a circular transverse cross-section.
The transition from the flattened portion to the portion having a circular cross-section defines a pair of axial shoulders, with which the element to be used for lifting engages. In order to increase the surface of these axial shoulders, the flattening of the tubular body at said transition can be considerable.
The element to be used for lifting has a hammer-like head, which can be inserted through the flattened axial end until it moves beyond the axial shoulders. After insertion, the element is turned about the axis of the tubular body with respect thereto, through an angle of substantially 90xc2x0, so that the two lobes of the hammer-like head face the two axial shoulders of the tubular body. The element is then locked rotationally with respect to the tubular body and its end arranged opposite the hammer-like head, which remains outside the tubular body and is slot-shaped, can be engaged by a hook of a lifting machine in order to lift the component.
Lifting inserts of this kind are generally provided in the formworks to be used to produce the prefabricated components, before pouring the concrete. Depending on the component to be manufactured, these lifting inserts can be associated with the sides of the formworks so that the axis of the tubular body is horizontal or can be suspended from cross-members or other horizontal supporting elements that lie between two opposite sides of the formworks.
In order to protect the inner portion of the lifting insert designed to receive the element to be used for lifting, a plug made of spongy material is used and is inserted beforehand in the tubular body.
The plug made of spongy material has the problem that due to its deformability it does not ensure a sufficient seal against the passage of concrete, which often invades the inside of the lifting insert, entailing manual interventions to remove it.
The tubular body is fixed to the sides of the formwork or suspended with often improvised manual methods, which do not always achieve the intended precision in the positioning of the lifting insert in the body of the prefabricated component.
The aim of the present invention is to solve the above mentioned problems, by providing a protection device for lifting inserts having a tubular body that avoids with absolute safety the infiltration of concrete, during the production of the prefabricated component into which the lifting insert is embedded, in the portion of the lifting insert that is designed to accommodate the element to be used for lifting the component.
Within the scope of this aim, an object of the invention is to provide a protection device that has a high mechanical strength and can be reused several times.
Another object of the invention is to provide a protection device that can also be used to support and position, with excellent precision, the lifting insert inside the formworks for the formation of the components.
Another object of the invention is to provide a protection device that is extremely simple and easy to use.
This aim and these and other objects that will become better apparent hereinafter are achieved by a device for protecting lifting inserts having a tubular body during their embedding in a prefabricated concrete component, characterized in that it comprises an elastically deformable element that can be inserted in the axial end of the tubular body of the lifting insert that is designed to be directed toward the outside of the prefabricated component and can be engaged by means for lifting the prefabricated component, said elastically deformable element being suitable to occupy an axial portion of said tubular body starting from said axial end, expansion means being provided which act on said elastically deformable element in order to cause a radial expansion thereof that engages said elastically deformable element with the inside walls of said tubular body in order to prevent the infiltration of concrete through said axial end of the tubular body of the lifting insert.